I went to Mexico City for spring break in 2004. This city was formerly Tenochtitlán, the capital of the empire of the Mexica (known by their subject peoples as the "Azteca"). The Spaniards were amazed at its size, cleanliness, and wealth. Hernán Cortés had to destroy it block by block in order to conquer it in 1521. Nueva España was the wealthiest and most important of Spain's colonies. Mexico is one of the three largest and wealthiest countries in Latin America. The revolution of 1910-17 gave it a socialist future that was foreclosed by the Institutional Revolutionary Party (PRI), although they retained the iconography and rhetoric.
Here you will find pictures of the main square ("Zócalo"), the Metropolitan Cathedral, the pyramids of Teotihuacán, the shrine to the virgin of Guadalupe, patron saint of Mexico, the fortress-monastery and ruins at Tlatelolco, the Palace of Fine Arts and the Alameda park, the Torre Latinoamericana skyscraper, various beautiful buildings in the city, the cloister of Sor Juana Inés de la Cruz, Mexico's greatest colonial poet and playwright, the National Palace with murals by Diego Rivera, and the Taller Tiempo Extra Editores art gallery.
Some things I did not have the time to see: The house of Diego Rivera and Frida Kahlo, the house of Leon Trotsky (where he was assassinated in 1940 while living in exile), the Castillo de Chapultepec (the last defense of Mexico City against the US Army in 1847), the lake at Xochimilco, the legislature, the national art museum, the national library, movies, the theater scene... those will come on the next trip.
Under construction.